Return mount's actual error codes instead of obfuscating them.
    
    In addition to being unnecessary, this obfuscation does not account for
    the fact that the codes can be combined using a bitwise or.
    
    This is part of the reason we were unable to identify the actual problem
    with the series of bugs involving the error "SystemError: (2, None)"
    during F11, F12, and perhaps after that.
    
    Related: rhbz#548592